1. Field
Embodiments of the invention relate to the field of networking; and more specifically, to the architecture of a Mobile Internet Protocol (IP) foreign agent architecture.
2. Background
Mobile IP is a protocol which allows laptop computers or other mobile computer units (referred to as mobile nodes herein) to roam between various sub-networks at various locations, while maintaining Internet and/or WAN connectivity. Mobility agents (e.g., home agent, foreign agent) provide mobile IP functionality. In a Mobile IP network, each mobile node is identified by its home address (assigned by a home agent), regardless of its current point of attachment to the Internet. While situated away from its home, a mobile node is also associated with a care-of address (provided by a foreign agent), which indicates its current point of attachment for reachability. While a mobile node is away from its home and connected to a foreign network it requests registration through the foreign agent to the home agent. If registration is successful, when the mobile node's home network receives packets addressed to the mobile node, the home agent will send those packets, over a tunnel, to the foreign agent which in turns forwards the packets to the mobile node. When the mobile node is sending packets, the foreign agent may employ reverse-tunneling and send the packets to the home agent who in turn forwards the packets to their destination, or the foreign agent may directly forward the packets to their destinations.
In a typical Mobile IP network, a service provider (e.g., a mobile service provider which provides services such as wireless network access) may belong to one or more home agents. Some of these home agents may be allocating IP addresses from a private address space while providing Internet connectivity through Network Address Translation (NAT) and there is a possibility that IP addresses assigned to the mobile nodes overlap. To support the overlapping address space, the prior art typically provisions a separate forwarding table for each overlapping address space. In addition, the home agents are typically paired with a foreign agent (e.g., FA-HA). The home agents may be paired with multiple foreign agents and the foreign agents may be paired with multiple home agents. For each pairing, there exists a tunnel between the foreign agent and the home agent, and a separate forwarding table for the pairing. As a single foreign agent may be paired with multiple home agents belonging to the same service provider, multiple forwarding tables may exist for the same service provider, which will store in part duplicative information. Additionally, another disadvantage of this prior art technique is that additional services relative to the service provider are difficult and/or inefficient to provide. For example, policies for the service provider (e.g., firewall, quality of service (QoS), packet filters, etc.) must be separately applied for each forwarding structure.
Additionally, the service provider also may be providing other services (e.g., broadband network access, virtual private network (VPN) services, etc.). In a typical network element, the routing structures for these other services are separate from the routing structures related to the Mobile IP network. Thus, a different routing domain exists for each type of service provided. Additionally, a typical service provider that provides mobile services as well as broadband network access service, VPN service, etc, requires multiple physical nodes to provide functionality for routing. Thus, a disadvantage of a typical network is that multiple routing structures each representing a type of service may exist for the service provider. Additionally, in a typical network element, polices applied to the network traffic related to the service provider (e.g., firewall, quality of service (QoS), packet filters, etc.) are applied to separately to each routing domain. Thus, in the case of a separate routing domain for each type of service, the same policies may be applied multiple times (e.g., the same policy is applied for Mobile IP traffic and broadband traffic).